Conventional foldable chairs of this type, for example, comprise a front stand made of a metal pipe and formed into a generally U-shape with a backrest provided at the upper open end thereof, a rear stand made of the same metal pipe as the front stand and formed into a generally U-shape, and a seat pivotally mounted to the front and rear stands, and have such a structure that as the front and rear stands are moved to approach each other, the seat is rotated toward the backrest to take an upright posture, thereby to fold the front and rear stands and the seat into a generally flat configuration.
In a foldable chair of the above structure, for example, the outer sides of the front and rear stands are connected through link members so that when the chair is folded, the front and rear stands overlap each other at both sides of the seat as viewed from the front or rear side.
Since the chair has such an arrangement that a link member is pivotally mounted to each leg of the front and rear stands to make a link mechanism of the seat and each link member so that the chair can be folded, not only the number of component parts e.g. the pins to be riveted but also the number of the manufacturing steps increase, with resulting increase in the manufacturing cost.
There is another foldable chair in which slide links are slidably provided at the top end of each of the rear legs and has its top end pivotally mounted to the outer sides of each of the front legs. In this chair, as the top ends of the slide links are connected to the outer sides of the front legs, the rear legs are placed on the outer sides of the front legs. As a result, the seat is supported away from the sides of the rear legs, thereby decreasing the strength to support the seat. In addition, as the rear legs are disposed outside the front legs, a plurality of such chairs arranged closely side by side require a broader space, thereby to decrease the efficiency to utilize space.
In order to solve these problems, a foldable chair has been proposed, in which a joint member is welded to the rear side of each front leg and the top end of a slide link is connected to the joint member. With the slide link using the above joint member, as the joint member is fixed to the rear side of each front leg, the front and rear legs overlap each other as viewed from the front or rear side when the chair is folded.
In the above arrangement, joint members should be provided in addition to the front and rear legs and the seat, thereby to increase the number of component parts. In addition, the welding of the joint members to the front legs must be conducted in a different working step outside the manufacturing line in which cutting and bending of pipe material is conducted. Therefore, the manufacturing line becomes complicated, and even though the line is automated, it is difficult to reduce the number of the manufacturing steps and consequently the manufacturing cost.